21217163730 has 128 divisors (see below), whose sum is σ = 58693939200. Its totient is φ = 4808312064.

The previous prime is 21217163729. The next prime is 21217163731. The reversal of 21217163730 is 3736171212.

It is an interprime number because it is at equal distance from previous prime (21217163729) and next prime (21217163731).

It is a junction number, because it is equal to n+sod(n) for n = 21217163691 and 21217163700.

It is not an unprimeable number, because it can be changed into a prime (21217163731) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 13608691 + ... + 13610249.

It is an arithmetic number, because the mean of its divisors is an integer number (458546400).

Almost surely, 2^21217163730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21217163730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29346969600).

21217163730 is an abundant number, since it is smaller than the sum of its proper divisors (37476775470).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21217163730 is a wasteful number, since it uses less digits than its factorization.

21217163730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2088.

The product of its (nonzero) digits is 10584, while the sum is 33.

The spelling of 21217163730 in words is "twenty-one billion, two hundred seventeen million, one hundred sixty-three thousand, seven hundred thirty".